Davis-Monthan Air Force Base will be using Arizona’s sun to cool its youth center by summer.

Sopogy Inc., a Hawaii-based energy company, is installing a new type of solar-energy system on the roof of the building that will use heat from sunlight to create chilled air.

The project is part of the military’s plan to cut installations’ energy costs.

The Department of Defense found that air conditioning accounts for 30 percent to 60 percent of its total facility energy expenditures. Officials decided that switching from fossil fuels to solar heat would help the department meet its renewable-energy targets.

Sopogy’s system uses heat from sunlight to create cool air in a process known as absorption chilling.

By May 1, there will be 72 mirrored “micro-concentrated” solar collectors, which are about 12-feet long, weigh less than 200 pounds and will provide about 66 tons of cold air, according to a Davis-Monthan spokesman.

The mirrors focus the sunlight on a pipe filled with a heat transfer fluid that runs to a solar absorption chiller, which reacts to the heat and creates cold air, said Darren Kimura, president and CEO of Sopogy.

The parabolic mirrors are motorized to track the sun’s movement, Kimura said. Most air-conditioning systems in the United States use a compressor and a refrigerant, which creates cold air but uses a large amount of electricity. Industrial absorption chillers are typically driven by natural gas or waste heat.

Kimura said Sopogy installed the first air-conditioning system using the technology in 2009 in California.

All of the materials used in the system are nonhazardous, Kimura said. The liquid that reacts with heat to make cold is lithium bromide, which is found naturally in ocean water.

“It takes the same reaction that you would find if you were on a beach on a hot day,” Kimura said. “There’s the hot sun but then that cool air, the cool breeze, that’s the same effect that the chiller has except the chiller is much more concentrated.”

Davis-Monthan will be the second military installation to use the technology. The first was Fort Bliss, near El Paso.

The company began working with NASA on the technology years ago, Kimura said, adding that the Pentagon identified Davis-Monthan as a prime site.

Sopogy’s system also will provide thermal storage and natural gas as backup for the cooling system on cloudy days.

“This gives you cold air 24 hours, seven days a week,” Kimura said, adding that the cost is less than half of the cost of electric refrigeration.

For now, the technology is only for businesses or big buildings like schools.

“We’re trying to downsize it so it can be cost-effective in your home and we’re not quite there yet,” Kimura said.

Michelle A. Monroe is a University of Arizona journalism student and a NASA Space Grant intern. Contact her at mmonroe@azstarnet.com

First project in Arizona to use Concentrated Solar Power with Dual Effect Absorption Chiller

Tucson, Arizona – February 3, 2012 – Chair of the White House Council on Environmental Quality, Nancy Sutley, will visit Davis-Monthan Air Force Base today to inspect an air conditioning project that will be fueled by the sun. In a collaborative RDT&E effort, ESTCP, the US Navy and NASA have partnered to build the solar air conditioning system on the Air Force Base. They have selected Sopogy, a Hawaii-based clean tech, as technology provider.

Sopogy’s technology is called MicroCSP for micro-concentrated solar power. MicroCSP is a renewable source of energy delivered through modular, parabolic solar collectors. Sopogy’s collectors are twelve feet long, and weigh less than two-hundred pounds.

At Davis-Monthan AFB, the solar air conditioning system will provide sixty-six tons of chilled air to the Youth Center. Seventy-two MicroCSP collectors will concentrate the sun’s heat onto receiver tubes carrying heat transfer fluid to fuel the chiller. The dual-effect absorption chiller generates cold air with heat, not electricity, the hotter the sun, the more effective the chiller. In addition to the solar collectors, Sopogy is providing proprietary thermal storage to back-up the cooling system. MicroCSP thermal storage is low cost relative to batteries. When clouds roll in, hot fluid will flow from storage to the chiller for continuous production.

Department of Defense studies have concluded that air conditioning accounts for 30-60% of its total facility energy expenditures. Switching from fossil fuels to solar heat will help the DOD to meet is aggressive renewable energy targets. The demonstration project at Davis-Monthan AFB is scheduled for completion in March 2012.

About Sopogy
Sopogy revolutionized solar thermal technology with Micro Concentrated Solar Power, or MicroCSP. Developing modular collectors about one-third the size of a traditional concentrated solar power mirror, Sopogy cut the cost of solar thermal energy to a fraction of the cost. Proprietary storage units stabilize volatile energy production when cloudy and prolong production after sunset. Please visit www.sopogy.org.